The present invention relates generally to saws used during the semiconductor device assembly process and, more particularly, to a saw with a self-sharpening blade used during semiconductor device assembly.
It is known to use saws during the assembly of semiconductor devices, such as for cutting dies from a wafer. Additionally, during the semiconductor device assembly process, multiple semiconductor devices can be formed simultaneously on a one- or two-dimensional assembly of lead frames called a lead frame array. In order to finish assembly of the semiconductor devices, the lead frames of the array undergo a singulation process using a saw or laser. Additionally, saws are used to singulate integrated circuit dies fabricated on semiconductor wafers. When using a saw to perform the singulation process, a self-sharpening saw blade may be used to maintain the sharpness of the saw blade.
FIG. 1A shows a stylized close up view of a portion of a self-sharpening saw blade 101. The self-sharpening saw blade 101 has pieces of material called grit 102, such as bits of diamond, embedded in a bond material 103, such as nickel. When the self-sharpening saw blade 101 cuts material, chip pockets 104 take the cut material away from the area where the cutting occurs. The chip pockets 104 also carry water to the cutting area for cooling.
The bond material 103 that holds the grit 102 is gradually worn away during the cutting process. As the bond material 103 wears away, grit that had been held within the bond material 103 falls away exposing new grit. The wearing away of the bond material 103 and the exposure of new grit is referred to as self-sharpening.
As shown in FIG. 1B, sometimes during the cutting process, the grit 102, bond material 103, and/or chip pockets 104 can be covered with a glaze 105 formed by the material from the objects being cut, such as silicon wafers. The glaze 105 can inhibit the self-sharpening function of the saw blade 101 and cause the saw blade 101 to damage the wafer being cut, causing die edge chipping or peeling.
It would be advantageous to have a self-sharpening saw for use in semiconductor device assembly that does not damage the integrated circuit dies being packaged.